1. Field of Invention
The invention relates to keyboards and more particularly to an illuminated keyboard with improved characteristics.
2. Description of Related Art
Laptops are widely used throughout the world. Typically, a laptop is equipped with a scissor-switch keyboard. In detail, a plurality of scissor switches each is mounted between a key and a base plate. Scissor-switch keyboards have the advantages including lightweight, low-profile, and easy operation. However, a user can only operate a laptop in an illuminated environment since back light arrangement is not provided by the laptop. Thus, sometimes their uses are not convenient.
A typical illuminated keyboard is characterized in that LEDs (light-emitting diodes) are attached to the bottom of a PCB (printed circuit board). LEDs may emit light upward to illuminate the PCB and components thereon. However, no light guide means for directing a uniform illumination to the keys is provided. Thus, some keys proximate to the LEDs are sufficiently lit and other keys distal the LEDs are dim. This can cause inconvenience in use.
Another typical illuminated keyboard is characterized in that a membrane circuit board is provided on an aluminum plate. Under the aluminum plate there is a backlight layer. LEDs are provided on the backlight layer. Light emitted by the LEDs is directed upward through holes of the aluminum plate and the circuit board onto the bottoms of keys. It is advantageous for being capable of effecting a uniform illumination to all keys. However, the combination of the circuit board, the aluminum plate, and the backlight layer can greatly increase thickness of the keyboard. This can compromise the low-profile feature of laptops. Thus, the need for improvement still exists.